PCB Trace Size Calculator

PCB Trace Width Formula:

\[ Width = \left[\frac{I}{k \times \Delta T^{0.44}}\right]^{0.725} \times (thickness)^{-0.43} \]

Current (I):

amps

Temperature Rise (ΔT):

°C

Copper Thickness:

oz/ft²

k Constant:

Trace Width (mils):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a PCB Trace Size Calculator?

Definition: This calculator determines the appropriate width for a PCB trace based on current, temperature rise, copper thickness, and material constant.

Purpose: It helps electronics engineers and PCB designers ensure proper current carrying capacity while preventing excessive temperature rise.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 formula:

\[ Width = \left[\frac{I}{k \times \Delta T^{0.44}}\right]^{0.725} \times (thickness)^{-0.43} \]

Where:

\( Width \) — Trace width (mils)
\( I \) — Current (amps)
\( \Delta T \) — Temperature rise (°C)
\( thickness \) — Copper thickness (oz/ft²)
\( k \) — Material constant (0.024 for internal layers, 0.048 for external)

Explanation: The formula calculates the minimum trace width needed to carry a given current without exceeding a specified temperature rise.

3. Importance of Proper Trace Sizing

Details: Correct trace sizing prevents overheating, ensures reliable current carrying capacity, and maintains signal integrity in PCB designs.

4. Using the Calculator

Tips: Enter the current in amps, desired temperature rise (default 10°C), copper thickness (default 1 oz/ft²), and k constant (default 0.024). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical temperature rise value?
A: 10°C is common, but higher values (20-30°C) may be used for power traces if the application allows.

Q2: How does copper thickness affect trace width?
A: Thicker copper allows narrower traces for the same current, as shown by the inverse relationship in the formula.

Q3: When should I use different k constants?
A: Use 0.024 for internal layers and 0.048 for external traces, as external traces dissipate heat less efficiently.

Q4: What's the minimum practical trace width?
A: While the formula may suggest very small widths, practical manufacturing limits are typically 5-10 mils for most PCB fabricators.

Q5: Does this account for high-frequency effects?
A: No, this is for DC/low-frequency current. High-frequency designs require additional considerations for impedance and skin effect.